Bistable electromagnetic valve

ABSTRACT

A bistable electromagnetic valve is proposed, which is to be used in refrigerant circuits. The valve can be produced at particularly low outlay and at the same time is reliably leaktight. This is achieved, according to the invention, in that the valve chamber ( 7 ) is formed within a control coil ( 3 ) by a cylindrical tubular body ( 2 ) which extends at least beyond the pole pieces ( 5, 6 ) inserted into the cylindrical tubular body ( 2 ).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a bistable electromagnetic valve characterizedby a valve chamber (7) arranged within a control coil (3) and the outerwall of the valve chamber (7) that is formed within the control coil (3)by a cylindrical tubular body (2) which extends at least beyond the polepieces (5, 6) inserted into the cylindrical tubular body (2).

2. Description of the Related Art Including Information Disclosed Under37 C.F.R. 1.97 And 1.98

Prior art valves of this type are used, for example, in refrigerantcircuits, such as are described in the publications DE 37 18 490 or BP10 54 200.

In such valves, a bistable situation is achieved by permanent magnetsbeing arranged outside the valve housing, next to the valve chamber ornext to the pole pieces, so that the valve body has, at the pole pieces,two end positions in which it is held by these permanent magnets.

High requirements in terms of leaktightness and long-term stability areplaced on such valves. Furthermore, as is customary, there is therequirement to produce such a valve as cost-effectively as possible.

BRIEF SUMMARY OF THE INVENTION

The object of the invention is, therefore, to propose a valve which canbe produced at little outlay and is reliably leaktight.

This object is achieved, starting from a valve for a refrigerant circuitof the type mentioned in the field of the invention characterized by avalve chamber (7) arranged within a coil (3) and the outer wall of thevalve chamber (7) that is formed within the coil (3) by a cylindricaltubular body (2) which extends at least beyond the pole pieces (5,6)inserted into the cylindrical tubular body (2).

Advantageous designs and developments of the invention are possible as aresult of the features described in the following description of theinvention including drawings and dependent claims.

Accordingly, a valve according to the invention is distinguished in thatthe valve chamber is arranged within the control coil and the outer wallof the valve chamber within the control coil is formed by a cylindricaltubular body. The tubular body in this case extends at least beyond thepole pieces inserted into the cylindrical tubular body.

This means that, in contrast to conventional valves, the pole pieces donot have the connections, but, instead, the latter are simply introducedinto the tubular body. Leaktightness problems between the tubular bodyand the pole pieces are consequently prevented completely at the lowestpossible outlay.

In a development of the invention, the tubular body is designed to be ofa length such that it extends at least as far as the end faces of thecontrol coil. Thus, even with the control coil put in place, the tubularbody is easily accessible. Moreover, the tubular body can be adapted tothe inside diameter of the coil, without connection points having to betaken into account.

Furthermore, in this case, fluid connections of the valve can beattached in a particularly simple way to the cylindrical tubular bodyaccessible outside the control coil.

A particularly simple design of such a fluid connection arises in thatat least one end of the tubular body is used as a tubular connection forthe fluid. In addition to a minimal number of sealing points, this, inturn, affords the advantage of extremely favorable manufacture, sincethe tubular connection is formed in the simplest instance by one end ofthe cylindrical tubular body which is already present in any case.

Preferably, further valve components are inserted into the tubular body.Those which come under consideration in this case are, for example, thepermanent magnets necessary for bistable functioning or else filterelements in order to filter dirt particles or, in general, impuritiesout of the fluid. In principle, however, further valve components mayalso be integrated readily into the cylindrical tubular body.

Dirt filters, which may be designed, for example, as a sieve tube orelse as a magnetic filter element for the separation of magnetic ormagnetizable particles, keep impurities away from the valve body and thevalve seat, so that the wear of these components is effectively reduced.This results, in turn, in a high long-term stability of the valve. It ispointed out particularly, at the same time, that such valves are usedconventionally in closed fluid circuits, so that the filter capacity hasto be sufficient merely for once-only purification of the fluid volumelocated in the circuit.

Moreover, it is advantageous to fix at least one of the said valvecomponents to the inside of the tubular body at least in the axialdirection. The valve thereby forms a unit capable of being handled inthe unconnected state, without the possibility of any valve componentsfalling out of the cylindrical tubular body on the end face.

Axial fixing can be achieved, for example, by the corresponding valvecomponent being pressed together with the tubular body inside thelatter. Such pressing can be implemented at little outlay, for example,by pressure on the tubular body from outside, and, in particular, even aplurality of valve components can be fixed in one operation.Furthermore, by pressing, a valve component can also be fixed reliablyin the radial direction.

In a simple embodiment, even a peripheral bead or a nose pressed in onthe outside may be sufficient for axial fixing. Thus, for example, allthe valve components may be designed in such a way that they have ineach case an abutment against one another, so that, by a bead or a nosebeing applied on both sides, the complete valve unit pushed into thetubular body is both fixed in the tubular body and secured againstrelative displacement by the mutual abutments.

In a further advantageous embodiment, an additional inner tube is pushedinto the tubular body at least on one side of the valve chamber. What isknown as a 3/2-way valve can also be produced in this way. The spacebetween the inner tube and the cylindrical tubular body accordinglyserves as an inflow line, in which case a duct to the inner valvechamber must be formed on or in the corresponding pole piece. In thesimplest instance, such a duct may be formed by a circumferential recesson the pole piece. The inner tube itself then forms an outflow for thefluid in one switching position of the valve body. In the otherswitching position, the opposite end of the tubular body can be used asan outflow.

BRIEF DESCRIPTION OF THE DRAWINGS

An exemplary embodiment of the invention is illustrated in the drawingand is explained in more detail below with reference to the figures ofwhich, in particular,

FIG. 1 shows a cross section through a 2/2-way valve according to theinvention;

FIG. 2 shows a cross section through a 3/2-way valve according to theinvention; and

FIG. 3 shows a cross section of a 2/2-way valve schematically connectedto a refrigerated appliance having refrigerated spaces a cold generatingcircuit including a compressor, condenser and evaporators.

DETAILED DESCRIPTION OF THE INVENTION

The valve 1 according to FIG. 1 comprises a cylindrical tubular body 2according to the invention as a valve housing which passes completelythrough a control coil 3. Adapter pieces 4 in this case ensure a goodfit in the valve housing 2 and are designed at the same time as fluxguide elements for an increased magnetic flux through pole pieces 5, 6and through a valve chamber 7. Inside the valve chamber 7 is located aspherical valve body 8 which, in the position illustrated, lies on thespherical seat 9 of the pole piece 6 and at the same time closes apassage bore 10. The passage bore 10 issues into the outflow line 11 ofthe valve 1.

The tubular body 2 extends into the space outside the coil 3 andtherefore also beyond the pole pieces 5, 6.

Annular magnets 12, 13 lying outside the tubular body 2 ensure thebistable behavior of the valve and are fixed by means of a spacer ring14 between the adapter pieces 4.

The pole piece 5 has in its outer circumference recesses or flatteningswhich produce fluid ducts 15 between the pole piece 5 and the tubularbody 2 into the inside of the valve chamber 7. The fluid ducts couldalso be implemented by bores in the pole piece 5, the inflow-sideorifices of said bores lying in the annular region between a tubularsieve 18 and the inner wall of the tubular body 2. The pole piece 5 has,furthermore, a spherical seat 16, in order to bring about a defined endposition of the valve body 8 in the second end position, notillustrated.

The pole piece 5 comprises a step 17, onto which the tubular sieve 18 ispushed. At the opposite end, the tubular sieve 18 is fixed in a magneticfilter 19 designed as an annular magnet. The tubular region of thetubular body 2 in which the tubular sieve 18 and the magnetic filter 19are located serves as an inflow line 20 for the corresponding fluid,that is to say, in particular, for refrigerant.

Inflowing fluid (see arrow P) passes first into the region of themagnetic filter 19, which is designed as an annular magnet, and comesdirectly into contact with the fluid. As a result, magnetic ormagnetizable dirt particles are already fixed permanently to themagnetic filter 19 at a considerable distance from the valve chamber 7.

The fluid subsequently passes into the inside of the tubular sieve 18which is closed on the end face, at the opposite end, by the pole piece5 or its step 17. The fluid flow accordingly has to take place radiallyoutward in the tubular sieve 18, dirt particles larger than the sieveorifices 21 of the tubular sieve 18 being retained in the interior ofthe tubular sieve 18. Thus, only purified fluid passes into the exterior22 between the tubular sieve 18 and the tubular body 2. The fluid passesfrom there, via the fluid ducts 15, into the inside of the valve chamber7.

The flow, of course, takes place only with the valve open, that is tosay in the switching position in which the valve body 8 lies on thespherical seat 16 and the passage bore 10 is released.

A valve 1 according to the invention can easily be built into a fluidcircuit, for example a refrigerant circuit, which, as a consequence ofmanufacture, contains dirt particles which are not compatible withconventional refrigerant valves and cause malfunctions.

The use of the valve 1 is aimed at closed fluid circuits which remainclosed after manufacture over the useful life of the valve 1. The filtercapacity of the filter system consisting of the tubular filter 18 and ofthe magnetic filter 19 must in this case be designed in such a way thatonce-only complete purification of the fluid located in the circuit,without clogging, can follow.

In this way, that is to say by the use of a filter 18, 19 in the inflowline 20 of the tubular body 2 and, in particular, by the directarrangement next to the valve chamber 7, an introduction of dirt intothe valve chamber 7 is reliably ruled out to an extent such thatpermanently leaktight and low-wear functioning of the valve 1 can beensured.

FIG. 2 corresponds essentially to the abovementioned exemplaryembodiment, in this case, by contrast, a second tubular outflow line 23leading into the inside of the tubular body 2 as far as the pole piece 5and being fixed there in a leaktight manner in a corresponding bore 24.The tubular body 2 and the outflow line 23 are closed off relative toone another, for example pressed or soldered, in a leaktight manner at asealing point 25.

An interspace 26, to which an inflow line 27 is connected, is thusobtained between the outflow line 23 and the tubular body 2. The inflowline 27 may, for example, be soldered in a corresponding orifice of thetubular body 2.

In this embodiment, the pole piece 5 also comprises a passage bore 28connecting the valve chamber 7 to the interspace 26 via the fluid ducts15.

The fluid or refrigerant can pass in the direction of the arrow P intothe interspace 26 and from there through the magnetic filter 19 into thein this case annular interior between the tubular sieve 18 and theoutflow line 23. The fluid subsequently flows radially outward into theexterior 22 between the tubular sieve 18 and the tubular body 2, fromwhere it passes via the fluid ducts 15 into the valve chamber 7.

The fluid then flows out either via the outflow line 23 or via theoutflow line 11, depending on the switching position of the valve body8. In the switching position illustrated, the passage bore 28 of thepole piece 5 is open, that is to say outflow takes place via the outflowline 23.

By means of a control pulse from the control coil 3, the valve body 8can be brought onto the opposite spherical seat 16, with the result thatthe passage bore 28 is closed and the passage bore 10 is opened. In thisswitching position described, but not illustrated, the fluid flows outvia the outflow line 11.

Instead of the adapter pieces 4 which have a conical outflow surfaceinside the control coil 3, in the present case sleeve-shaped flux guideplates 29, which completely fill the interspace between the tubular body2 and the control coil 3, are provided for guiding the magnetic fluxinside the control coil 3. The flux guide plates 29 are in each caseconnected to a closing plate 30 which itself is connected to what areknown as yoke plates, not illustrated in any more detail, or merges intothese. The flux guide plates 29 may be punched, bent or wound togetherwith the closing plate 30 and the entire yoke plate arrangement, notillustrated in any more detail, out of a flat material.

LIST OF REFERENCE SYMBOLS

-   1 Valve-   2 Tubular body-   3 Control coil-   4 Adapter pieces-   5 Pole piece-   6 Pole piece-   7 Valve chamber-   8 Valve body-   9 Spherical seat-   10 Passage bore-   11 Outflow line-   12 Annular magnet-   13 Annular magnet-   14 Spacer ring-   15 Fluid duct-   16 Spherical seat-   17 Step-   18 Tubular sieve-   19 Magnetic filter-   20 Inflow line-   21 Sieve orifice-   22 Exterior-   23 Outflow line-   24 Bore-   25 Sealing point-   26 Interspace-   27 Inflow line-   28 Passage bore-   29 Flux guide plate-   30 Closing plate

1. A bistable electromagnetic valve with a valve chamber arrangedbetween two pole pieces and with a valve body which is displaceabletherein between two end positions and which is designed as a magneticarmature for at least one permanent magnet and for at least one controlcoil wherein the improvement comprises said valve chamber (7) arrangedwithin said control coil (3) in which the outer wall of the valvechamber (7) is formed within the control coil (3) by a cylindricaltubular body (2) which extends at least beyond the pole pieces (5, 6)inserted into the cylindrical tubular body (2).
 2. The bistableelectromagnetic valve according to claim 1 wherein said cylindricaltubular body extends at least as far as the end faces of the controlcoil (3).
 3. The bistable electromagnetic valve of claim 1 or 2 whereinfluid connections (11, 20) of the valve (1) are formed on thecylindrical tubular body (2).
 4. The bistable electromagnetic valve ofclaim 1 or 2 wherein at least one end of the cylindrical tubular body(2) forms a tubular connection (11, 20) for a fluid.
 5. The bistableelectromagnetic valve of claim 1 or 2 wherein valve components (18) areinserted into the cylindrical tubular body (2).
 6. The bistableelectromagnetic valve of claim 1 or 2 further comprising a dirt filter(18) inserted into the cylindrical tubular body (2).
 7. The bistableelectromagnetic valve of claim 1 or 2 wherein at least one valvecomponent (5, 6, 18) is fixed to the inside of the cylindrical tubularbody (2) in the axial direction.
 8. The bistable electromagnetic valveof claim 1 or 2 wherein at least one valve component (5, 6, 18) ispressed together within said cylindrical tubular body (2).
 9. Thebistable electromagnetic valve of claim 1 or 2 wherein at least one beador nose is pressed into the cylindrical tubular body (2) for the axialfixing of a valve component (5, 6, 18).
 10. The bistable electromagneticvalve of claim 1 or 2 wherein an inner tube (23) is pushed into thecylindrical tubular body (2) on one side of the valve chamber (7).
 11. Abistable electromagnetic valve of claim 1 or 2 further comprising acold-generating circuit for a refrigerating system having a plurality ofrefrigerating spaces, a compressor, a condenser, a plurality ofevaporators which are assigned to at least one of the refrigeratingspaces wherein said bistable electromagnetic valve connects thecondenser to one or more of the evaporators according to predeterminedoperating states.
 12. A bistable electromagnetic valve of claim 1 or 2further comprising a refrigerated appliance with a cold-generatingcircuit wherein said refrigerated appliance includes a cold-generatingcircuit having said bistable electromagnetic valve.
 13. A method forproducing a bistable electromagnetic valve with a valve chamber arrangedbetween two pole pieces and with a valve body displaceable thereinbetween two end positions and which is designed as a magnetic armaturefor at least one permanent magnet and for at least one control coilwherein the improvement comprises the step of introducing valvecomponents (5,6, 18) into a substantially cylindrical tubular body (2)containing said valve chamber extending out at least as far as the endfaces of the control coil and using said substantially cylindricaltubular body (2) as the outer wall of the valve chamber (7) andarranging said pole pieces (5,6) completely within said substantiallytubular body (2).
 14. A bistable electromagnetic valve article ofmanufacture comprising: (a) a control coil housing having a first endface and a second end face; (b) a substantially cylindrical tubular bodydisposed within said control coil housing having ends extending at leastas far as said first end face and said second end face of said controlcoil housing; (c) a valve chamber disposed in said substantiallycylindrical tubular body intermediate the first end face and said secondend face of said control coil housing; (d) a first pole piece disposedin said substantially cylindrical tubular body intermediate said valvechamber and one of said ends of said substantially cylindrical tubularbody; (e) a second pole piece disposed in said substantially cylindricaltubular body intermediate said valve chamber and the other of said endsof said substantially cylindrical tubular body; and (f) a magnetdisposed outside said substantially cylindrical tubular body adjacent tosaid valve chamber.